Quantum phase transitions in coupled two-level atoms in a single-mode cavity

Abstract

The dipole-coupled two-level atoms(qubits) in a single-mode resonant cavity is studied by extended bosonic coherent states. The numerically exact solution is presented. For finite systems, the first-order quantum phase transitions occur at the strong interatomic interaction. Similar to the original Dicke model, this system exhibits a second-order quantum phase transition from the normal to the superradiant phases. Finite-size scaling for several observables, such as the average fidelity susceptibility, the order parameter, and concurrence are performed for different interatomic interactions. The obtained scaling exponents suggest that interatomic interactions do not change the universality class.

Quantum phase transition in the one-dimensional Dicke-Hubbard model with coupled qubits

“…It is this change of the angular momentum across the phase boundary results in the unexpected first-order quantum phase transition between the Mott-insulating phase and the Superfluid phase. Similar phenomenon has been previously observed in the Dicke model with coupled two-level atoms in a single cavity [38]. Finally, by using the same criterion, we numerically confirm that the quantum phase transitions between different N in the Mott-insulating phase are all first-order.…”

“…Since multiple qubits are injected in a single cavity, the qubit-qubit interaction may not be negligible. In fact,the intracavity interaction among qubits has been studied in the generalized Dicke model where dipole-coupled qubits interact with a single cavity mode [38]. A phase diagram with both first-and second-order coherent-incoherent phase transitions are observed.…”

Dynamic sensitivity of quantum Rabi model with quantum criticality

“…Then the high-order terms which contain the average photon number cannot be ignored. In this case, the approximate Hamiltonian (13) will not be valid as λ > λ c . To achieve the effective Hamiltonian in this case, we introduce a displacement operator D(α) = exp[α(a † − a)] to make a transformation upon Hamiltonian (1) [15] ĤRabi 26) can be expressed as [15] ĤRabi…”

“…Consequently, an interesting question is whether quantum phase transition can take place in a finite-component system. It has recently been shown that quantum phase transition can take place in simple systems [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. An advantage of this kind of systems is that the systems have less degrees of freedom, and hence those previous mentioned difficulties in infinite-component systems can be improved [22].…”

Quantum entanglement of the binomial field interacting with a cascade three-level atom beyond the rotating wave approximation

“…Dattoli et al [7] found in 1987 that the binomial state could occur in the free electron laser. Since then, many different properties of the binomial states, such as squeezing [8] and anti-bunching [9] Recently, the interaction between the atom and the field is widely studied [10][11][12][13][14]. Compared with the two-level atom, the three-level atom has different transition characteristics.…”